This invention relates to a contactless, electronic magneto ignition system, and more particularly to a control system for controlling the ignition timing in accordance with the rotational speed of an internal combustion engine ignited by switching an ignition system.
Conventional engine ignition systems of the type referred to have been previously arranged to generate an ignition signal at each of the ignition times of the internal combusion engine, and switching a semiconductor switching element such as a thyristor or a transistor with the ignition signal to induce an ignition voltage across the secondary side of an ignition coil. Therefore, the ignition time has been naturally determined by a waveform for the ignition signal generated in synchronism with the rotation of the engine. In other words, these conventional ignition systems have been able to respond to spark advances required for preventing the occurrence of the reverse rotation of the engine in the low speed range but they have been unable to fulfill the requirements for the spark receding characteristics and the other characteristics necessary to maintain the horsepower output of the engine in the moderate to high speed range.
Also, conventional electronic ignition time control systems of the type referred to have been arranged to control the determination of a time at which the particular engine is to be ignited, by sensing the rotational speed of the engine before the necessary ignition time thereof. However the rotational speed of engines vary greatly in a low speed range and particularly during the start of engines. Under these circumstances, if the ignition time would be controlled by sensing the rotational speed of an engine before the necessary ignition time thereof, then the ignition time determined at that time is not the proper ignition position required for the engine. That is, an ignition position thus determined is extremely delayed with respect to the required ignition position. In addition, an amount of that delay has been sharply changed with the result that a stable ignition time is not provided.
Accordingly, it is an object of the present invention to eliminate the disadvantages of the prior art practice as described above by the provision of a new and improved magneto ignition system capable of providing the ignition timing characteristics at a moderate and a high speed range of an internal combustion engine.